Discovered Jupiter-like planet orbiting a white dwarf: a snapshot of the future of the solar system
When it was first observed in 2010, scientists had almost no hope of identifying the star around which the massive planet orbited. More than 5,000 light-years from Earth, the star in the system to which the Jupiter-like planet belongs was finally identified only in 2018, after years of searching.
And the study by astrophysicist Joshua Blackman of the University of Tanzania, who is leading the research, reveals an exceptional possibility: that of seeing in the newly identified system the future of planets orbiting the Sun.
The future of the Sun: white dwarfs
After years of observations using the world’s most powerful telescopes, Blackman’s team had come to the conclusion that it would never be possible to detect a Sun-like star near the planet.
“We spent several years trying to figure out why,” Blackman explains, “why the star we expected to see was not visible from Earth.” The only possible conclusion is that it is not a “main sequence” star like the Sun at all, but an object of another type.
The observed star, which is located in the constellation Sagittarius, has a mass that does not exceed half that of the Sun, which allowed to exclude both the neutron star hypothesis and the possibility that it was a black hole – objects much, much larger than the one under observation.
After more than a decade of study, Blackmore broke the silence and published in Nature the final hypothesis: it would be a white dwarf star.
A white dwarf is formed when a star similar to the Sun explodes to become a red giant and releases all its outer layers to reveal a hot core. That core is what will eventually become, in the life cycle of stars, a white dwarf.
The Sun will become a white dwarf in about 7.8 billion years: the discovery could be, according to Blackman, “a snapshot of the future of our solar system.”
A glimpse into the future of the solar system
The system discovered by the Australian team, then, could reveal much about the future of planets orbiting the Sun. In addition to showing the future of our star, which will inevitably turn into a white dwarf, the new system bears an exceptional resemblance to our own: a planet very similar to Jupiter.
The Jupiter twin, which has been spotted by scientists well before the star it orbits, is estimated to have about twice the mass of the solar system’s planet, and to be about five times farther from its star than Jupiter.
The planet must be, Blackman continues, much larger than its star – whose size should be similar to Earth’s. It is the first planet ever discovered to orbit a white dwarf, and the resemblance to Jupiter was immediately apparent to scientists.
It is believed that when our Sun becomes a red giant, long before it turns into a white dwarf, it will swallow up the nearest planets: certainly Mercury, and perhaps Venus.
Mars, Jupiter and other more distant planets will survive to rotate, perhaps, around the Sun that has become a small white star of frightening density. Starting here, the study of the planet identified by Blackman may tell us a lot about the more distant future of the solar system.